Where is the edge of the world according to flat-earthers? The answer changes, but it usually involves some impenetrable barrier at said edge that prevents people from going past or falling off. Global conspiracies apparently prevent people from investigating these boundaries yet no one has ever seen this huge barriers that go around the world. humans have circumnavigated the planet in planes and ships, and no one has fallen into space. Rather, when ships traveling large distances on the ocean do appear and disappear on the horizon, they do so either mast or hull-first, respectively. If the Earth was flat, and you had the right optics, you could watch a ship sail from New York to Africa without losing sight of it.
Hit up a friend in Australia and ask them what constellations they can see at night. Now tell them which ones pepper your patch of darkness. They wont be the same. Because the Earth is a shape other than a flat disk, when looking into the night sky the Earth itself can block your view.
If the flat Earth theory were true, everyone should be able to see the same constellations all the time, as if we all were staring up from the same section of summer grass.
Don't assume you can see through dense atmosphere at great distances anymore than you can see through a stack of plate glass.
Don't assume the sky is flat when making claims about what we should see if we weren't stuck to the surface of a spinning ball in a vacuum by a magical force proven to exist only by two lead balls in a 17th century shed. As far as I'm aware the dome is a concave mirrored surface, this is going to distort what you see along with perspective when your vantage point changes and create star configurations like the southern cross.
